These drugs, called fibrates, modestly reduce blood levels of artery-clogging bad cholesterol, raise good cholesterol and are most effective at lowering levels of other damaging blood fats called triglycerides, although the overall picture from clinical trials remains confusing.

Fibrates include gemfibrozil (Lopid), which got the regulatory nod in 1981; fenofibrate (TriCor, Triglide), approved in 2007, and the closely related drug fenofibric acid (TriLipix, Fibricor), which entered the U.S. pharmaceutical marketplace in December 2008. In 2009, fenofibrate and fenofibric acid together accounted for almost 74 percent of the U.S. market share of fibrates, the researchers said. While fenofibric acid isn't available in Canada, bezafibrate (Bezalip) is available in Canada but not in the United States.

The increase in fibrate prescriptions, driven by a 200 percent jump in the use of fenofibrate, has outpaced the growth of statins, according to an analysis of U.S. and Canadian fibrate use appearing in the current issue of JAMA. But, to keep things in perspective: statins, which are among the most commonly prescribed medications, remain blockbuster drugs that dominate lipid-lowering treatment, with fibrates accounting for just 9.4 percent of the U.S. lipid-lowering market in 2009.

The study authors found that U.S. prescriptions for fibrates grew from 336 per 100,000 people in January 2002, to 730 per 100,000 people in December 2009. That's a 117.1 percent hike. At the same time, Canadian prescriptions for fibrates held nearly steady, at 402 per 100,000 in early 2002 and 474 per 100,000 in late 2009.

"The use of fibrates in America is very troubling," said Dr. Steven E. Nissen, chairman of cardiovascular medicine at the Cleveland Clinic Foundation. Noting that fibrates are among medications advertised directly to consumers, he said: "This is a classical example of marketing triumphing over science." He described the increasing use of fibrates as an expensive failure to educate doctors and regulators.